The present invention relates to coverings for solar cells and mole specifically to sol-gel coatings for solar cells.
Solar cell technology is continuing to develop as a renewable and sustainable energy option. Generally, a solar cell converts radiant energy into usable electrical energy. When in use, solar cells are typically shielded from damaging effects of the environment, such as radiation, by a protective device or covering on the surface of the solar cells. Currently, glass coverings are applied to the surfaces of the solar cells. The glass cover is often heavy and fragile however, and may include a labor-intensive installation process. A typical glass cover slide is a slide that ranges from about 2 to about 12 milli-inches (hereafter xe2x80x9cmilsxe2x80x9d) in thickness to allow processing without breakage, and a silicone liquid or pressure Sensitive adhesive to attach the slide that ranges from about 2 to about 3 mils in thickness. Glass cover slide systems, however, contribute to the overall weight of a solar cell array, complicate the manufacturing process and increase the likelihood of breakage due to the fragile quality of the glass.
Therefore, there is a need in the art for a light weight, durable protective coating for solar cells and provide adequate radiation damage resistance. There is also a need in the art for a simplified method of providing solar cell protection and electrical insulation which is transparent over a wavelength range suitable for transmitting radiant energy into the solar cell. There is a further need in the art for a protective layer for use as a dielectric separator between solar cell substrates in multi-junction solar cells.
Methods for providing solar cells having improved radiation damage resistance by applying sol-gel coatings onto the surface of the solar cells. The sol-gel coatings transmit an acceptable level of radiant energy into the solar cell while providing adequate radiation damage resistance. In one embodiment, a method for preparing a coating is disclosed comprising a water-borne binder system, such as a silicon-zirconium binder system, to form a sol-gel coating on a surface of a solar cell. The sol-gel coating provides a lightweight and durable solar cell surface coating that transmits radiant energy into the solar cell while providing adequate radiation damage resistance.
In an additional embodiment, a method for preparing a sol-gel coating for a solar cell is disclosed comprised of mixing organosilane, zirconium alkoxide, a catalyst such as acetic acid, a solvent such as water and optionally surfactant, wherein ratio of organosilane to zirconium alkoxide is about 1 part organosilane to about 2 parts zirconium alkoxide to form a sol-gel solution. The sol-gel solution may be concentrated to form a sol-gel coating which can be applied to and cured on a surface of a solar cell.
In an additional embodiment, a method of depositing a sol-gel coating onto a surface of a solar cell is provided comprising spraying a water-borne sol-gel coating onto a surface of a solar cell to form a sol-gel coating of suitable dimension.
In other embodiments, products of the disclosed methods are provided which include solar cells, such as gallium arsenide solar cells, having improved radiation damage resistance.
While the principal advantages and features of the present invention have been described above, other features and advantages and a more complete and thorough understanding of the invention may be attained by referring to the brief description of the drawings, detailed description and appended claims and drawings.